1. Field of the Invention
The invention relates generally to display of fonts on a video system and to BIOS programming, and more particularly to a BIOS for a graphics system and improving that BIOS.
2. Description of the Related Art
Designers of computer systems use a BIOS chip to store firmware which the system utilizes either for low-level functions or initialization routines. Because the BIOS is used only at the start of the computer or for low-level routines it is not economical for it to take up a lot of space either physically or in memory. Those parts of the BIOS routines which are used more frequently still should be optimized for speed and optimized for storage space so that they do not significantly consume memory that would be otherwise utilized by actual application programs or the operating system typically used on a computer. Thus, economizing on code or other data stored in BIOS is of the utmost priority in the design of the BIOS. More recently, BIOS chips have been utilized in subsystems such as graphic systems to implement functions which are used repeatedly. Those functions are preferably stored in the BIOS in a processing efficient and space efficient manner. Thereby, the functions can be executed quickly by the processor, are easily available to the programmer, and do not take up a lot of space either physically on the board or in the logical memory space addressable by a video or graphics processor.
The implementation of BIOS for graphic subsystems has been used in laptop computers where a limitation of 48K or 48 kilobytes of space was available. However that convention is also becoming more common in desktop systems, and in desktop systems the graphics BIOS is limited to 32K because of older conventions of the VGA graphics subsystems. Therefore, it is desirable to find a way to save memory space when implementing the BIOS, in particular when implementing the BIOS for a desktop graphics subsystem.
Typically, the BIOS of a graphics system will have four fonts stored within it. These include 8×8, 8×14, 9×14, 8×16, and 9×16 fonts. In the case of the 8×14 font, each character is 8 pixels wide and 14 pixels high when displayed on the screen. With these fonts available in the BIOS, programmers can always rely on their presence for use with application programs. Typically, the 8×14 and 8×16 fonts have characters which are 7 pixels wide and the eighth column of pixels is always left blank, thereby allowing the characters to be placed side-by-side without having them appear too close to each other. Likewise, the 9×14 and 9×16 fonts are typically used only when a programmer wishes to have a customized character. The programmer programs the characters to be used in the 9×14 or 9×16 font, specifying whether each pixel will or will not be turned on, and any characters not programmed in the 9×14 or 9×16 font default to the corresponding character in the corresponding 8×14 or 8×16 font.